Adjustable drafting triangle



2 Shee ts-Sheet 1 Aug. 24, 1937. H. MEYER ADJUSTABLE DRAFTING TRIANGLE Filed DeC. l2, 1956 Aug. 24, 1937. H. MEYER l ADJUSTABLE DRAFTING TRIANGLE Filed Deo. l2, 1936 2 Sheets-$11661I 2 feye?" ATTO RN EY .m Em. v mg n@ @Un Y xe Patented Aug. Z4, i937 OFFICE.

Application December l2, 1936, Serial No. 115,458 ln Germany December 17, 1935 13 Claims.

l() an adjustable triangle the legs of which may be moved easily and without the help of springs or the like from a Zero position, i. e. the position in which one leg forms the straight line continuation of the other one into any desired position up to the position in which the legs cover each other.

rlhe invention essentially consists of an elongated frame or casing forming the base of the drafting triangle and two leg members pivotally connected at one oi their ends, the other ends being symmetrically movable within said casing by means of a drive or gearing.

The invention furthermore contemplates the provision of lugs at those leg ends which are movable within said casing, and two guiding members being symmetrically movable lengthwise within said casing. Said legs are pivoted at the guiding members respectively, and the pivots at the guiding members and the pivots at the opposite ends of the legs are so arranged as to lie always at the corners oi a geometric triangle.

Further objects and details of the invention will be apparent from the description hereinafter, and the annexed drawings showing an embodiment of my invention by way of example. In the drawings are:

Fig. 1 a front elevation of a device according to my invention in the zero position in which the legs are parallel with the base of the drafting triangle;

Fig. 2 a top View; Fig. 3 a sectional view along line 2-2 of Fig.

6; solid lines indicating the same position of the legs as in Fig. l, and dash lines indicating a posi- 5 tion in which the legs include angles of 45 degrees with the base;

Fig. 4 a partial view similar to Fig. 3, the legs being in the position where they include angles of 90 degrees with the base of the triangle;

Fig. 5 a section along line 5-5 of Fig. 4;

Figs. 6 to 8 sections along lines 6 6, l-l and 8 8 respectively of Fig. 3, and

Fig. 9 a rear view.

Referring now to the figures, l is a casing 55 forming the triangle base and which may be placed on a T-square when the adjustable triangle is being used. The casing consists of a frame member 2 having U-shaped cross-section, a front plate 3 and a back plate 4 both secured to frame 2. I prefer to make part 2 of metal and 5 plates 3 and 4 of wood or other suitable nonmetallic material. Casing l together with two movable legs 5 and 5a forms the adjustable trangle. The legs 5 and 5a which may be made of any suitable material preferably have Z-shaped cross-sections (see Fig. 5), the top flanges d5 and a being considerably wider than the bottom flanges 4S and ila which rest on the drawing surface when the device is in use. One of the legs, for instance, leg E, is higher than the other one that is to say its web 4l is higher than web Ma, so as to permit overlapping of the legs as clearly shown in Figs. 4 and 5. The top ends of the legs are pivotally connected by a'pin t. The lower ends of the legs are passed through a lon- 20 gitudinal slot 48 in the top wall of the casing frame 2. The center portion of slot 48 is wider than its side portions 49 and 49a, and the side portions are staggered, so as to permit the flanges l5 and 45a of the legs 5 and 5a respectively to move in diierent planes. Furthermore, the lower ends of webs 41 and lila are provided with recesses 5B and 59a and back plate f1 is provided with recesses 5I and Ela, in order to make allowance for the movements of the lower ends of flanges 4t and 46a. The lower ends or" flanges 45 and 45a have inwardly projecting lugs I and la respectively, pivot pins 9 and Sa passing therethrough. The front portion of the casing is provided at its inside with two parallel recesses or grooves Ei and lla at different heights of the casing, the grooves extending from near the opposite ends of the casing beyond its middle portion. Two guiding members or rods lil and ma are slidably arranged within said recesses or 4() grooves ll and lla. respect1vely. Guiding member lll has a downwardly extending projection l Hl,

and guiding member loa has an upwardly extending projection llla, said projections carrying the afore-mentioned pivot pins 9 and Sa so that the latter maybe moved along one and the same straight line when members lll and ma slide in their respective grooves il and lla.. Near the ends of the casing, two rollers I2 and 12a are rotatably mounted, and a turning knob i6, arranged at the front side of the casing, is rigidly connected with one of the rollers, for instance l2. Flexible members I3 are attached to the ends of the guiding members, and are passed about the rollers so that upon turning of knob I one of the guiding members will slide in its pertaining groove from the one side to the other side while the other guiding member moves in the opposite direction. Each roller is pivoted on a sled ifi beingshiftable within casing I by means of screws I5 and IEa passing through the end walls of the casing. In order to permit such shifting of roller I5, the casing and front plate 3 have an elongated slot 30 in which the shaft 3l carrying both roller I5 and knob I6 may move. By turning screws I5 and I 5a, or only one of them in such a direction that the pertaining sleds or sled are or is moved towards the end of the casing the iiexible members I3 may be stretched,

and by turning the screws so as to shift both sleds in the same direction the center position of legs 5 and 5a may be adjusted.

Means are provided for setting the legs at a denite angle with respect to each other. For

this purpose, the top of leg 5 carries a scale I'I on which corner IIa of leg 5a indicates the adjusted angle. Instead of scale I'I or in addition thereto, in the latter case as an alternative means, the front side of casing I inclusive front plate 3 may be provided with a longitudinal slot I8 opposite which an indicator I9 may travel and indicate, at scales 2l and 22 alongside slot I8, the angle enclosed by the legs or the grade of the inclination of the legs with respect to the base.

For this purpose indicator I9 may be fastened to any suitable portion of the movable parts I0, Ilia and I3.

As clearly shown in Fig. 3, pivots 9 and 9a are located considerably below pivot 8, and constitute therewith a geometric triangle even if the legs are in zero position (Fig. 3). This geometric triangle is suiciently high to cause the legs to rise from zero position easily and without the help of springs or equivalent means when their lower ends are being moved towards each other.

Complete erection of the legs to 90 degrees with respect to the base (Fig. fl) is made possible by the difference in the height of the webs of the Z-shaped legs which permits them to overlap each other, and by the arrangement of lugs III! and itil-a in diiferent planes'whereby pivots 9 and 9a, may pass each other beyond the center line of the apparatus.

When legs 5i and 5a are brought into the position in which the axes of pivots 9 and 9a are in line the legs 5 and 5a might be swung together towards the left or the right hand side. In order to prevent such movement, recesses 5I and Ela of back plate 4 are so shaped that their edges form guiding faces to support the lower corners 52 and 52a of the leg flanges d5 and 46a when pivots 9 and 9a are close to each other.

The adjustable triangle according to my invention offers many advantages among which are the following:

Very small angles of only a few degrees over zero and below 90 degrees may be set.

The legs may be readily erected from their completely stretched position.

The legs cannot spring even if in an almost horizontal position.

The apparatus does not require additional arresting means, because any alteration of an adjusted position requires opposing movements of 70 the lower ends of the legs which prevents undesired shifting due to one-sided pressure during the drafting.

Although I have described a particular embodiment of my invention I do not wish to re- 75 strict myself to the illustrated structure since many alterations and modifications are possible within the scope of the invention. For instance any other suitable drive for the movement of the triangle legs may be used instead of the drive employing flexible means.

I claim:

1. An adjustable drafting triangle comprising a base member, two leg members, a pivot connecting said two leg members at one of their ends, and two other shiftable pivots for the other ends of said leg members respectively in connection with said base member, said leg members having a zero position in which they are collinearly extended and parallel with said base member, and being adjustable between said zero position and an erected position, said three pivots being located at the corners of a geometric triangle with said rst mentioned pivot above said other pivots when said leg members are in zero position.

2. An adjustable drafting triangle comprising a base member, two leg members having equal length, a pivot connecting said two leg members at one of their ends, two other shiftable pivots for the other ends of said leg members respectively, and means on said base member for moving said shiftable pivots symmetrically with respect to said rst mentioned pivot, said leg members having a Zero position in which they are collinearly extended and parallel with said base member and a fully erected position in which they overlap each other, and being adjustable between said zero position and said fully erected position, both said leg members and said base member having rear surfaces in an identical plane, and said three pivots being located at the corners of a geometric triangle with said first mentioned pivot above said other pivots when said leg members are in zero position.

3. An adjustable drafting triangle comprising a base member, two leg members having equal length, a pivot connecting said two leg members at one. of their ends, two other shiftable pivots for the other ends of said leg members respectively, means on said base member for moving said shiftable pivots symmetrically with respect to said rst mentioned pivot, said leg members having a fully erected position at right angles to said base member, in which they overlap each other, and a zero position in which they are collinearly extended and parallel with said base member, and being adjustable between said Zero position and said fully erected position, said two shiftable pivots being movable along parallel lines so as to be capable of passing each other, and said three pivots being located at the corners of a geometric triangle with said first mentioned pivot above the other pivots when said leg members are in zero position. y

4. An adjustable draftingr triangle comprising a base member, two leg members of equal length and Z-shaped cross-section, one flange of which being narrower than the other one and being adapted to rest upon a drafting surface, and the web of one of said legs being shorter than that of the other one, so as to permit said legs to overlap each other, a pivot connecting said two leg members at one of their ends, two other shiftable pivots for the other ends of said leg members respectively, said two shiftable pivots being movable along parallel lines so as to be capable of passing each other, and means on said base member for moving said last mentioned pivots symmetrically with respect to said first mentioned pivot.

5. An adjustable drafting triangle comprising a' base member, two` legmembers of equal length, a 'pivot connecting said two leg members at one of their ends, two other shiftable pivots for the other ends ci said leg members respectively in connection with said base member, said shiftable pivots being arranged in different planes so as to be able to pass` each other, means for moving said shiftable pivots symmetrically with respect to said first mentioned pivot, said base member having a length of not less than twice the length of one of said leg members and enclosing said shiftable pivots and'said moving means, and means at the outside of said base for controlling said moving means, said leg members having a Zero position in which they are collinearly extended and parallel with said base member, andv being adjustable. between said zero position and an erected position, said three pivots being located at the corners of a geometric triangle when said leg members are in zero position.

6. An adjustable drafting triangle comprising a base member, two leg members of equal length, a pivot connecting said two leg members at one of their ends, two other shiftable pivots for the other ends of said leg members respectively in connection with said base member, an endless drive including a pulling portion and a pulled portion, one of said last mentioned pivots being attached to said pulling portion and the other one to said pulled portion, said last mentioned pivots being arranged in different planes other than the plane defined by said pulling and said pulled portion of the endless drive, said drive being arranged within said base member, and means at the outside of said base member for operating said drive, said leg members having a Zero position in which they are collinearly extended and parallel with said base member, and a fully erected position in which they overlap each other, and being adjustable between said zero position and said erected position, said three pivots being located at the corners of a geometric triangle with the first mentioned pivots above the other pivots when said leg members are in zero position.

7. In an adjustable isosceles drafting triangle, a drive for shifting the base ends of the legs symmetrically with respect to the altitude of the triangle, comprising an endless member having flexible portions and including a pulling portion and a pulled portion, two rollers of equal diameter for guiding and driving said endless member, the center of said rollers being arranged on a line parallel to the base line of the drafting triangle, means connected to said pulling portion sideways thereof and projecting towards said pulled portion and means connected to said pulled portion sideways thereof and projecting towards said pulling portion'for articulately attaching the base ends of the triangle legs respectively said projecting means being arranged in different planes, and means for adjusting the position of the axes of said rollers in the direction of the line connecting the centers of said rollers, so as to stretch said endless member by increasing the distance o of said rollers from each other, and to shift the center line of the triangle sideways by shifting both rollers in the same direction.

8. In an adjustable isosceles drafting triangle, a base member, two leg members articulately connected at their top ends, and a drive within said base member for moving the base ends of said leg members symmetrically with respect to the altitude of the triangle, said drive comprising two rigid elongated parts, two flexible parts connecting the ends of said rigid parts and forming therewith an endless member, two rollers of equal diameter for guiding and driving said flexible parts, said base member having two parallel grooves extending from points near the opposite of said rollers.

9. An adjustable isosceles drafting triangle comprising a base member having a top wall and a rear wall, two leg members of Z-shaped crosssection, said leg members being articulately connected at their top ends and being adapted to overlap each other when their base ends are brought together, the top wall of the base member being slotted and recessed and the rear wall being recessed to permit the base ends of the leg members to enter into the base member, the base ends of the front flanges of the Z-shaped leg members each having a sideways projecting lug, a drive within said base member, said drive including parts movable symmetrically with respect to the altitude of the triangle and being articulately connected with said lugs, and means for operating said drive from the outside of said base member.

10. An adjustable drafting triangle comprising a base member, two leg members of equal length and Z-shaped cross-section, one flange of which being narrower than the other one and being adapted tov rest upon a drafting surface, and the web of one of said legs being shorter than that of the other one so as to permit said legs to overlap each other, a pivot connecting said two leg members at one of their ends, two other shiftable pivots for the other ends of said leg members respectively, said two shiftable pivots being movable along parallel lines so as to be capable of passing each other, guiding means for said leg members at said base member for preventing said leg members from swinging in the same direction when the axes of said shiftable pivots are in line, and means within said base member for moving said last mentioned pivots symmetrically with respect to said first mentioned pivot.

11. An adjustable drafting triangle comprising a base member consisting of a metallic part of U-shaped cross-section, and a non-metallic rear plate covering the flanges of the U-shaped crosssection, two leg members having equal length and including each a lateral projection at its base end, said projections protruding through recesses into said base member, a pivot connecting said two leg members at their top ends, two other shiftable pivots in different planes for the projections of said leg members respectively within said base member, means for moving said shiftable pivots symmetrically with respect to said first mentioned pivot, said three pivots being located at the corners of a geometric triangle when said leg members are in Zero position in which they are collinearly extended, said moving means being attached to the metallic part of said base member Within its U-shaped cross-section.

l2. An adjustable isosceles drafting triangle comprising a base member having a top wall and a rear wall, two leg members of Z-shaped crosssection, said leg members being articulately connected at their top ends and being adapted to overlap each other when their base ends are brought together, the top wall of the base member being slotted and recessed to permit the base ends of the leg members to enter into the base member, the rear wall of the base member being recessed, the edges of the rear wall recesses forming abutments for the rear flanges of said legs When approaching their erected position, the base ends of the front flanges of the Z-shaped leg members each having a sideways projecting lug, a drive within said base member, said drive including parts movable symmetrically with respect to the altitude of the triangle and being articulately connected with said lugs, and means for operating said drive from the outside of said base member.

13. An adjustable drafting triangle comprising an elongated member forming the triangle base, two leg members each having a lateral projection of its base end, a pivot connecting said two leg members at their top ends, two shiftable pivots for connecting said base member with said lateral projections, said leg members having a zero position in which they are collinearly extended and parallel with said base member, and being adjustable between said zero position and an erected position, and said three pivots being located at the corners of a geometric triangle with the first mentioned pivot above the other pivots when said leg members are in zero position.

HANS MEYER. 

